I've run my Renix with both the EGR and without and never really noticed much difference. It's supposed to help when running regular gas and help lower the burn temperatures some, which is supposed to aid in a more complete combustion.
My Renix is doing very nearly the same thing as yours (and my EGR is hooked up and functioning at present). I don't know yet exactly what is causing the problem (though it was a lot worse). My IAC acts up on occasion and I have low and high idle, which seems to be related to the temperature of the motor. When my motor temp. is a bit high, the idle lowers and it will sometimes stall at a stop (very occasionally). I also seem to have a periodic high idle at start up and it also seems to run a bit rough on occasion. Most of this never happens when the motor is running cool or during the warmup period. It makes me want to test the temp sensor for the computer, I'm guessing I may have a dirty connector that is messing with the resistance values. It also makes me think it's something in the fuel control system, O2, MAP or another sensor.
I still haven't made up my mind if it is fuel, ignition, a sensor or low voltage someplace due to excess resisitance in some circuit.
I also tested my CPS, which is about 290 ohms when hot, which is just out of the envelope of 200 +/- 75 ohms the book calls for. But I really don't know how much I trust the CPS ohm test, I have two CPS's in my spares box now that test almost exactly 200 ohms and don't work. My rear main seal is slinging oil pretty good, which may have soaked the CPS and is causing problems. I've had the CPS act up in the past when they got wet, I'm guessing they aren't sealed very well. My TPS tested good and is set correctly.
After I check out my temp senor resistance and the wiring resistance, I'll let you know what I find. If it is way out, it may be a likely place to start.
Your problems sounds very near to what I have going on. Though mine was running a lot worse, it ran almost like it was dieseling (on occasion), I couldn't bring the RPM's up no matter how I feathered the gas, it ran like absolute crap, but kind of cured itself after a restart, it's only happened a few times (hasn't happend since I cleaned my grounds, connectors, relays and swapped out the MAP). My ignition system seems to be generally in pretty good shape, the tune up is good. Cap, plugs, wires and the other stuff all seems OK. Though I did find a couple of plug cables that had backed out of the cap a little.
It is said, that the Renix has no memory, but mine envariably runs better (for awhile anyways) after I disconnect the battery for awhile.
Sorry if I provided more problems than solutions, I'm still thinking this new set of symptoms out.
Most of this stuff started up, after my coolant surge tank sprung a leak and pissed all over the right side of the motor, the relay block and the connectors. I don't really know if the coolant bath and my troubles are related or not. I've cleaned all of my grounds and most of the connectors, including the relay block, the relay plugs were pretty corroded. Cleaning the relay sockets, seemed to help some, but the problem hasn't completely gone away (it seems to be getting better in small steps). I'm thinking the B+ latch relay and/or the fuel pump relay were adding to my problems, maybe excess resisitance in those circuits at the relay. I swapped out my MAP at about the same time I cleaning the relays (which seemed to help some), but mine is still doing what yours is doing, just to a lesser degree than before.
